Elementary particle

In particle physics, an elementary particle is a particle of which other, larger particles are composed. For example, atoms are made up of smaller particles known as electrons, protons, and neutrons. The proton and neutron, in turn, are composed of more elementary particles known as quarks. One of the outstanding problems of particle physics is to find the most elementary particles - or the so-called fundamental particles - which make up all the other particles found in Nature, and are not themselves made up of smaller particles.

The Standard Model of particle physics contains 12 species of elementary fermions ("matter particles") and 12 species of elementary bosons ("radiation particles"), plus their corresponding antiparticles and the still undiscovered Higgs boson. However, the Standard Model is widely considered to be a provisional theory rather than a truly fundamental one, since it is fundamentally incompatible with Einstein's general relativity. There are likely other elementary particles not described by the Standard Model, such as the graviton, the particle that would carry the gravitational force or the sparticles, supersymmetric partners of the ordinary particles.

Quarks also carry fractional electric charges, but since they are confined within hadrons whose charges are all integral, fractional charges have never been isolated. Note that quarks have electric charges of either +2/3 or -1/3, whereas antiquarks have corresponding electric charges of either -2/3 or +1/3.

One major extension of the standard model involves supersymmetric particles, abbreviated as sparticles, which include the sleptons, squarks, neutralinos and charginos. Each particle in the Standard Model would have a superpartner whose spin differs by 1/2 from the ordinary particle. In addition, the sparticles are heavier than their ordinary counterparts: they are so heavy that existing particle colliders would not be powerful enough to be able to detect them. However, some physicists believe that sparticles will be detected by 2008 in the Large Hadron Collider at CERN.

According to string theorists, each kind of fundamental particle corresponds to a different resonant vibrational pattern of a fundamental string (strings are constantly vibrating in standing wave patterns, similar to the way that quantized orbits of electrons in the Bohr model vibrate in standing wave patterns). All strings are essentially the same, but different particles differ in the way their strings vibrate. More massive particles correspond to more energetic vibrational patterns. But fundamental particles do not contain strings: they are strings.

String theory also predicts the existence of gravitons. Gravitons are impossible to detect experimentally, because the gravitational force is so weak compared to the other forces.

Robert Rutkiewicz: Defining Mass Citat: "...The value of mass is not being redefined. But the concept of mass being a fundamental property is reviewed...A new physical law is postulated: All known particless are elements of momentum moving at a velocity c...This extension is based on special relativity and uses SR equation for mass..."

Milo Wolff: The Physical Origin of Electron Spin - using quantum wave particle structure Citat: "...The electron's structure, as well as its spin, had been a mystery. Providing a physical origin of spin for the first time is the purpose of this paper....note that spin, and other properties, are attributes of the underlying quantum space rather than of the individual particle. This is why spin, like charge, has only one value for all particles...This structure settles a century old paradox of whether particles are waves or point-like bits of matter. They are wave structures in space. There is nothing but space. As Clifford speculated 100 years ago, matter is simply, "undulations in the fabric of space". ..."